# Two Phase Flow In Vertical Pipe

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 October 29, 2017, 14:54 Two Phase Flow In Vertical Pipe #1 New Member   Stone preston Join Date: Oct 2017 Posts: 7 Rep Power: 8 I am trying to model a two phase flow in a vertical pipe using a boiling model. I used the 2nd part of this tutorial to guide my process. The problem I am trying to model is given below: A vertical steel tube carries water at a pressure of 10 bars. Saturated liquid water is pumped into the D = 0.1 m diameter tube at its bottom end (x = 0) with a mean velocity of um= 0.05 m/s. The tube is exposed to combusting pulverized coal, providing a uniform heat flux of q” = 100,000 W/m2. The total length of the pipe is 30 meters. A small piece of my mesh is shown here: https://imgur.com/a/fT73G I followed the tutorial to setup the eulerian boilding mode. I copied the liquid water and water vapor materials from the fluent database, setup the two phases, and specified the phase interactions. I made sure to change the saturation temperature in the boiling mass transfer mechanism to the saturation temperature at 10 bar. I specified the inlet velocity as .05 m/s for the liquid phase, and 0 for the vapor phase (since its a saturated liquid at the inlet). I also specified a gage pressure of 1000000 at the inlet for the mixture and 0 pressure at the outlet for the mixture. When I try to initialize, I get the following error: Code: ```Initialize using the hybrid initialization method. Checking case topology... -This case has both inlets & outlets -Pressure information is not available at the boundaries. Case will be initialized with constant pressure iter scalar-0 1 0.000000e+00 2 0.000000e+00 3 0.000000e+00 4 0.000000e+00 5 0.000000e+00 6 0.000000e+00 7 0.000000e+00 8 0.000000e+00 9 0.000000e+00 10 0.000000e+00 hybrid initialization is done. # Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0# Divergence detected in AMG for ads-0: protective actions enabled! # Divergence detected in AMG for ads-0, temporarily solve with BCGSTAB! Divergence detected in AMG solver: ads-0 Error at host: floating point exception Error at Node 0: floating point exception Error: floating point exception Error Object: #f``` How can I resolve this error? Is the problem with my mesh? Here is my mesh check: Code: ``` Domain Extents: x-coordinate: min (m) = 2.078713e-01, max (m) = 2.578713e-01 y-coordinate: min (m) = 0.000000e+00, max (m) = 3.000000e+01 Volume statistics: minimum volume (m3): 1.320992e-07 maximum volume (m3): 7.924628e-03 total volume (m3): 1.413717e+02 minimum 2d volume (m3): 4.204847e-06 maximum 2d volume (m3): 4.204847e-05 Face area statistics: minimum face area (m2): 4.204847e-04 maximum face area (m2): 1.000000e-02 Checking mesh............................ Done.``` and my mesh quality: Code: ```Mesh Quality: Minimum Orthogonal Quality = 1.00000e+00 (To improve Orthogonal quality , use "Inverse Orthogonal Quality" in Fluent Meshing, where Inverse Orthogonal Quality = 1 - Orthogonal Quality) Maximum Aspect Ratio = 2.38031e+01```

 October 30, 2017, 16:38 #2 New Member   Stone preston Join Date: Oct 2017 Posts: 7 Rep Power: 8 anyone have any ideas? Could really use some help/input

 October 31, 2017, 08:35 #3 Member   Jaesan Yoon Join Date: Sep 2017 Posts: 36 Rep Power: 8 I cannot check your *.cas file, then I couldn't convince that when there is a problem in initialization process, it might be problem in B.C set up... or How about using standard initialization rather than hybrid one?

 Tags fluent, two phase boiling, vertical pipe